Method of fabricating hollow pads



April 11, 1939.

M. A. SAVAGE METHOD OF FABRICATING HOLLOW PADS Original Filed June 24, 1956 I5 Fig]. l 5 :4 S '4 Fig.2. g 1

I26. l0 lZa i 12 Fig. 5. 2' '0 n n n n n H n fl n n H n I! n 11 II II II I 20 I9 Inventor: Marion A.Sava e,

b PVaMjTJ y Hi Attorney Patented Apr. 11,1939 I METHOD OF FABRIGATING HOLLOW PADS Marion A. Savage, Scotia, N. Y., asaignor to GeneYralkElectric Company, a corporation of New or 1 Original application June 24, 1936. Serial No,

86,966. Divided and this application April 8, 1937, Serial No; 135,751

7 Claims. (01. 29-1513) My invention relates to cooling pads which intermediate strip l9 spaced from the wall beare primarily adapted for insertion between tween thenipples I4 and I! to form a sinuous bundles of laminatlons in dynamo-electric mapassageway which extends between the openings chine core structures for removing heat therein the pad provided by the nipples. The ends 5 from. These cooling pads have substantially lila 01' thesestrips are slightly spaced from the li parallel fiat face portions which make contact adjacent flanges of the sheet II to slidably rewith the bundles of laminations and transfer the ceive the flanges of the sheet Hi. In the resulting heat from the laminations to a cooling fluid cirpad construction the strips l9 are thus spaced culated through the pad. from one another and alternately form opposite 10 In my application, Serial No. 86,966, flled June flanged portions of the sheets I 0 and II to form 10 24, 1936, for Cooling pad" I have described the sinuous passageway referred to. Additional and claimed a cooling pad of improved construcstrips 20, having the same width as the strips l9, tion. The present application is a division there are also attached to the inner surfaces of the of and covers the method of fabrication described body portions of the sheets I 0 and ii and extherein. tend along the central portion of the passage- 15 For an understanding of my invention referway formed by the strips l9. The ends of these ence may be had to the following description additional strips are spaced from one another at taken with the accompanying drawing in which points opposite the central portions of the strips Fig. l is a perspective view of a pad made in i8 to provide for a pressure equalization of the 2 accordance with my invention and embodying cooling fluid flowing on opposite sides of these the structural features thereof; and Figs. 2 to 7 strips through the passageway defined by strips inclusive, are views illustrating the structure of IS. Strips l9 and 20 serve to reinforce the pad the pad shown in Fig. 1, as well as the proagainst the compressive force exerted on its cedure by means of which this pad is fabricated. face portions in the assembled core structure The hollow cooling pad shown in the drawing of a dynamo-electric machine. These strips 25 forms the subject matter of my above referred also act as baflles by means of which the cooling to application. It has two substantially ,parfluid is directed in a predetermined path which allel faces formed by the body portions of two brings it into intimate contact with the total sheets l0 and II, the edges of which have been surface portion of the cooling pad.

turned up to form flanges I2 and I3. These For some applications one of the external faces 30 flanges are turned toward one another to space of the pad may be provided with cooling flns 2| apart the body portions of the sheets and are attached thereto in any desired arrangement integrally attached to one another throughout such as illustrated in Fig. 1. their lengths to form the edge walls of the pad, The method of fabricating this cooling pad is as well as the side walls of two flared nipples as follows: I4 and I5 formed by projections arranged one Two metallic sheets l0 and II are placed one within the other and extending from the edge of upon the other in a press by means of which the pad. The configuration of the pad and the their edge portions I2 and iii are simultaneously location of the nipples will depend on the use turned up to form pans which closely flt one to which the pad is put. In the construction 11- within the other, as shown in Fig. 3. The excess 40 lustrated, the lower portion of the pad is divided metal 22 at the rim of these pans is simultaneby a slot l6, which forms finger-like portions ously removed from the turned up portions of I! and I8 opposite the side from which the the sheets to form flanges of substantially uninipples project. This'slot I6 is made to accomform width. The inner pan formed of sheet Ill 43 modate windings located in the slots of laminais then separated from the outer pan formed 45 tions forming the core structure of a dynamoby sheet H. Additional metal, above the line electric machine and between which laminations "a in Fig- 4, is emo d from s turned up the pad is located. edge portion l2, to facilitate the assembly of Metal strips IQ of substantially the same width these sheets with their flanges turned toward as the width of the flanges of the sheets in and overlapping one another to form the hollow 50 and II are attached to the inner sl'n'faces of the Po of e P body portions of the sheets l0 and H. As shown The sheets are then preferably cleaned by imin Fig. 7, these strips are laterally spaced from mersing them in hot water, a cleaning solution, one another with the outer strips [9 spaced from or a pickling bath, to remove oil and dirt therethe ends of the portions l1 and i8, and with the from, and the surfaces of the sheets where they 5 are to be attached to one another and to the strips II, "and 2| are preferably roughened by suitable means such as steel grit directed thereon through the agency of an air blast. Strips II and III are then attached by welding them at intervals. as indicated at "b and Ilb, to the innersurface of the body portion of sheet II, as shown in Fig. 6. Strips 2| are then attached. preferably by welding, to the outer surface of the body portion of the sheet II, as shown in Fig. 5. The turned up edges of the sheets l8 and II and their surface areas, as well as the surface areas of the strips Is. it and 2|, are then coated with a brazing material such as copper, which may be applied thereto as a molten metal spray. The parts are then assembled as shown in Fig. 8 withthe edge of sheet turned over the body portion of sheet ill and the projections constituting the nipples I4 and II formed around one another thus bring the edge portions of the sheets in close contact with one another. The assembly is then placed in a brazing furnace with the assembly resting on the outside surface of the body portion of the sheet Any suitable arrangement for applying a. pressure to the assembly may be placed in engagement with the flns 2 The brazing operation is preferably performed in a hydrogen furnace to effect that species of brazing known as hydrogen brazing. In the presence of an atmosphere of hydrogen the copper brazing material readily flows into the crevices of the assembled parts and unites them one to the otherin a manner closely approaching the condition of a welded union. The pad after the brazing operation is an integral structure in which all the parts are firmly attached one to another through their contacting areas by the hydrogen brazing operation.

The nipples I4 and I5 are flared to facilitate the attachment therein of metallic conduits, the ends of which can be soldered to the nipples by puddling the solder in the annular space provided by their flared portions. I prefer to perform this soldering operation by using a silver solder, melted by the flame of a welding torch in the presence of a fluxing material.

The metal of the pad structure may be of anysuitable kind, but I prefer to use for the sheets i and ii and the strips i9 and 20, a copper nickel alloy known to the trade as Monel metal. I use this material because of its resistance to corrosion as well as its high electrical resistance which prevents undue heating due to eddy current losses in the pad when used as part of the core structure of a dynamo-electric machine. The fins 2| may be made of a low carbon steel or any other suitable material. These fins are provided to space the pad from an adjacent bundle of laminations and form passageways for the circulation of cooling gas between the pad and the bundle of laminations. These fins 2| may or may not form. part of the pad structure. When used they also serve to conduct heat from the bundle of laminations placed in contact therewith to the pad and to the cooling fluid circulated in the pad.

It is, of course, apparent that variations may be made in the structure of the pad, as well as in the procedure by means of which the pad is fabricated without departing from my invention. For example, the parts may be attached to one another by welding. Furthermore, the flanged edge portions of the sheets need not necessarily overlap one another, and may be provided with rims for facilitating certain welding operations.

'pad, and integrally It is also apparent tha the strips II, 20 and 2| are not necessarily attached throughout their lengths to the sheets l0 and ii, althoughsuch construction strengthens the pad and facilitates the transfer 'of heat through the strips II to the body portion of the plate to which they are attached.

What I claim as new and desire, to secure by Letters Patent of the United States is:

l. The method of making a hollow pad which comprises superimposing two metal sheets oneupon the other, simultaneously turning up the edge portions of said sheets to form pans which closely fit one within the other, removing excess metal from the turned up portions of said pans to form flanges of uniform width, separating. reversing and assembling said pans with their hollow portions forming the hollow portion of the uniting the turned-up portions of said pans.

2. The method of making a hollow pad which comprises superimposing two metal sheets one upon the other, simultaneously turning up the edge portions of said sheets to form pans which closely flt one within the other, simultaneously removing excess metal from the turned up portions of said pans to form flanges of uniform width, separating, reversing and fltting the pans one within the other with their hollow portions forming the hollow portion of the pad, and integrally uniting the turned up portions of said pans.

3. The method of making a hollow pad which comprises superimposing two metal sheets one upon the other, simultaneously turning up the edge portions of said sheets to/form pans which closely fit one within the other, simultaneously removing excess metal from the turned up portions of said nested pans to form flanges of uniform width, separating the inner pan from the outer pan, attaching spaced metal strips of substantially the same width as said flanges to the inner body surface of one of said pans, reversing and fitting said pans one within the other with their hollow portions enclosing said strips and forming the hollow portion of the pad, and uniting said pans and said strips into an integral structure.

4. The method of making a hollow pad which comprises superimposing two metal sheets one upon the other, simultaneously turning up the edge portions of said sheets to form pans which closely fit one within the other, simultaneously removing excess metal from the turned up portions of said nested pans to form flanges of uniform width, separating the inner pan from the outer pan, attaching to the inner surface of one of said pans metal strips spaced from one another and alternately from opposite edge walls of said pan to form a sinuous passageway which occupies substantially all of the hollow portion of said pan, reversing and fitting said pans one within the other with their hollow portions enclosing said strips and forming the hollow portion of the pad, and uniting said pans and said strips into an integral structure.

5. The method of making a hollow pad which comprises superimposing two metal sheets one upon the other, simultaneously turning upthe edge portions of said sheets to form pans which closely flt on'ia within the other, simultaneously removing excess metal from the turned up portion of said nested pans to form flanges of uniform width, separating the inner pan from the outer pan and removing additional metal from its flanged edge portion, attaching to the inner surface of one of said pans metal strips of substantially the same width as said flanges and spaced from one another and alternately from opposite edge walls of said pan to form a sinuous passageway which occupies substantially all of the hollow portion of said pan, applying a' brazing material to said pans at said strips and at their turned up edges, fitting said pans one within the other with their hollow portions enclom'ng said strips and forming the hollow portion of the pad, and uniting said pans and said strips into an integral structure by heating them to the melting temperature of said brazing material.

'6. The method of making a "hollow pad which comprises superimposing two metal sheets one upon the other, simultaneously turning up the edge portions of said sheets to form pans which .closely fit one within the other, simultaneously removing excess metal from the turned up portions of said nested pans to form flanges of uniform width, separating the innerpan from the outer pan and removing additional metal from its flanged edge portion, welding at intervals to the inner surface of one of said pans a plurality of metal strips of substantially the same width as said flanges and spaced from one another and alternately from opposite edge walls of said pan to form a sinous passageway which occupies substantially all the hollow portion of said pan, ap-. plying a brazing material to said pans at said strips and at their turned up edge portions, fitting said pans -one within the other with their hollow portions enclosing said strips and forming the hollow portion of the pad, and uniting said pans heating them to the melting temperature of said brazing material. I

7. The method of making a hollow pad which comprises superimposing two metal sheets one upon the other, simultaneously turning up the edge portions of said sheets to form pans which closely fit one within the other, simultaneously removing excess metal from the turned up portions of said nested pans to form flanges of substantially uniform width, separating the inner pan from the outer pan and removing additional metal from its flanged edge portion, cleaning the surfaces of said pans, roughening the surfaces of said pans and of metal strips to be attached thereto at their surfaces of contact when assembled, welding at intervals to the inner surface of one of said pans a group of said metal strips spaced from one another and alternatelyfrom opposite edge walls of said pan to form a sinuous passageway which occupies substantially all the hollow portion of said pan, welding-at intervals to the outer surface of the other of said pans a group of said metal strips in spaced relationship relative to one another, spraying a coating of copper on said strips, on the surfaces of said pans where said strips are attached and on the flanged edge portions of said pans, fitting said pans one within the, other with their hollow portions forming the hollow portion of the pad, placing said pans and strips in a brazing oven with the strips on said pans extending in an upward direction and integrally uniting said strips and said .pans by melting said copper coating in said furnace in an atmosphere of hydrogen.

' MARION A. SAVAGE.

and said strips into an integral structure by 

